The impact of increased oxygen conditions on metal-contaminated sediments part II: Effects on metal accumulation and toxicity in aquatic invertebrates

2012 ◽  
Vol 46 (10) ◽  
pp. 3387-3397 ◽  
Author(s):  
M. De Jonge ◽  
J. Teuchies ◽  
P. Meire ◽  
R. Blust ◽  
L. Bervoets
Keyword(s):  
Aquatic Invertebrates ◽  
Metal Accumulation ◽  
Contaminated Sediments ◽  
Oxygen Conditions ◽  
The Impact

scholarly journals Diagenetic formation of uranium-silica polymers in lake sediments over 3,300 years

2021 ◽  
Vol 118 (4) ◽  
pp. e2021844118
Author(s):  
Pierre Lefebvre ◽  
Alkiviadis Gourgiotis ◽  
Arnaud Mangeret ◽  
Pierre Sabatier ◽  
Pierre Le Pape ◽  
...  
Keyword(s):  
Contaminated Sediments ◽  
Mining Areas ◽  
Subsurface Environments ◽  
Geochemical Reactivity ◽  
High Silica ◽  
Long Term Behavior ◽  
The Impact ◽  
X Ray Absorption

The long-term fate of uranium-contaminated sediments, especially downstream former mining areas, is a widespread environmental challenge. Essential for their management is the proper understanding of uranium (U) immobilization mechanisms in reducing environments. In particular, the long-term behavior of noncrystalline U(IV) species and their possible evolution to more stable phases in subsurface conditions is poorly documented, which limits our ability to predict U long-term geochemical reactivity. Here, we report direct evidence for the evolution of U speciation over 3,300 y in naturally highly U-enriched sediments (350–760 µg ⋅ g−1 U) from Lake Nègre (Mercantour Massif, Mediterranean Alps, France) by combining U isotopic data (δ238U and (234U/238U)) with U L3-edge X-ray absorption fine structure spectroscopy. Constant isotopic ratios over the entire sediment core indicate stable U sources and accumulation modes, allowing for determination of the impact of aging on U speciation. We demonstrate that, after sediment deposition, mononuclear U(IV) species associated with organic matter transformed into authigenic polymeric U(IV)–silica species that might have partially converted to a nanocrystalline coffinite (UIVSiO4·nH2O)-like phase. This diagenetic transformation occurred in less than 700 y and is consistent with the high silica availability of sediments in which diatoms are abundant. It also yields consistency with laboratory studies that proposed the formation of colloidal polynuclear U(IV)–silica species, as precursors for coffinite formation. However, the incomplete transformation observed here only slightly reduces the potential lability of U, which could have important implications to evaluate the long-term management of U-contaminated sediments and, by extension, of U-bearing wastes in silica-rich subsurface environments.

scholarly journals Looking beyond stratification: a model-based analysis of the biological drivers of oxygen deficiency in the North Sea

2016 ◽  
Vol 13 (8) ◽  
pp. 2511-2535 ◽  
Author(s):  
Fabian Große ◽  
Naomi Greenwood ◽  
Markus Kreus ◽  
Hermann-Josef Lenhart ◽  
Detlev Machoczek ◽  
...  
Keyword(s):  
North Sea ◽  
Oxygen Deficiency ◽  
Low Oxygen ◽  
The North ◽  
Oxygen Conditions ◽  
Southern Central ◽  
The North Sea ◽  
Central North Sea ◽  
The Impact ◽  
Oxygen Dynamics

Abstract. Low oxygen conditions, often referred to as oxygen deficiency, occur regularly in the North Sea, a temperate European shelf sea. Stratification represents a major process regulating the seasonal dynamics of bottom oxygen, yet, lowest oxygen conditions in the North Sea do not occur in the regions of strongest stratification. This suggests that stratification is an important prerequisite for oxygen deficiency, but that the complex interaction between hydrodynamics and the biological processes drives its evolution. In this study we use the ecosystem model HAMSOM-ECOHAM to provide a general characterisation of the different zones of the North Sea with respect to oxygen, and to quantify the impact of the different physical and biological factors driving the oxygen dynamics inside the entire sub-thermocline volume and directly above the bottom. With respect to oxygen dynamics, the North Sea can be subdivided into three different zones: (1) a highly productive, non-stratified coastal zone, (2) a productive, seasonally stratified zone with a small sub-thermocline volume, and (3) a productive, seasonally stratified zone with a large sub-thermocline volume. Type 2 reveals the highest susceptibility to oxygen deficiency due to sufficiently long stratification periods (>  60 days) accompanied by high surface productivity resulting in high biological consumption, and a small sub-thermocline volume implying both a small initial oxygen inventory and a strong influence of the biological consumption on the oxygen concentration. Year-to-year variations in the oxygen conditions are caused by variations in primary production, while spatial differences can be attributed to differences in stratification and water depth. The large sub-thermocline volume dominates the oxygen dynamics in the northern central and northern North Sea and makes this region insusceptible to oxygen deficiency. In the southern North Sea the strong tidal mixing inhibits the development of seasonal stratification which protects this area from the evolution of low oxygen conditions. In contrast, the southern central North Sea is highly susceptible to low oxygen conditions (type 2). We furthermore show that benthic diagenetic processes represent the main oxygen consumers in the bottom layer, consistently accounting for more than 50 % of the overall consumption. Thus, primary production followed by remineralisation of organic matter under stratified conditions constitutes the main driver for the evolution of oxygen deficiency in the southern central North Sea. By providing these valuable insights, we show that ecosystem models can be a useful tool for the interpretation of observations and the estimation of the impact of anthropogenic drivers on the North Sea oxygen conditions.

Influences on the natural reproduction of whitefish (Coregonus lavaretus) in Lake Constance

2009 ◽  
Vol 66 (4) ◽  
pp. 547-556 ◽  
Author(s):  
Bernd Wahl ◽  
Herbert Löffler
Keyword(s):  
Age Structure ◽  
Lake Constance ◽  
Coregonus Lavaretus ◽  
Low Oxygen ◽  
Stock Size ◽  
Natural Reproduction ◽  
Lake Bottom ◽  
Oxygen Conditions ◽  
Spawning Time ◽  
The Impact

The conditions for the natural reproduction of whitefish ( Coregonus lavaretus ) in Lake Constance have been subject to strong variations during recent decades by the impact of fishing and trophic changes. We analysed fluctuations of stock size, age structure, spawning time, and amount of sampled eggs of this species. The onset of spawning altered because of changes in the age structure of the stock. We found a clear relation of spawning time to the mean age of the annual catch and the November epilimnion temperature. The quantity of eggs sampled from the lake bottom with a dredge is in relation to the number of female spawners and may serve as an early indicator for stock size changes. The proportion of viable eggs on the lake floor correlates with oxygen concentrations in deep water. Extremely low oxygen conditions and an almost total loss of eggs occurred when the nutrient levels were high and oxygen regeneration by vertical winter mixing was weak. A mathematical model serves to interpret the changing abundance of living eggs on the lake bottom over the course of a season and is also used to estimate mortality rates.

scholarly journals Trace metal accumulation in decapods and its use in monitoring the marine environment

2021 ◽  
Author(s):  
◽  
Annie Graham
Keyword(s):  
Trace Metals ◽  
Trace Metal ◽  
Spatial Variation ◽  
Marine Environment ◽  
Metal Accumulation ◽  
Environmental Indicators ◽  
Trophic Levels ◽  
Geochemical Data ◽  
Feeding Strategies ◽  
The Impact

<p>Coastal habitats are susceptible to severe contamination due to their exposure to both marine and terrestrial inputs, many of which contain toxic heavy metals. Trace metals in the marine environment can have severe impacts on the health of coastal ecosystems, as even those with essential functions can be toxic at high concentrations, and non-essential elements can cause impairment of biological functions even at low levels.  It is important to understand the chemistry of New Zealand’s marine environment, in order to successfully monitor any changes to the chemical profile of the environment from anthropogenic pollutants. Biological indicators are a useful tool for monitoring ecosystem health, and the impact of human activity on the environment. Crustaceans fulfil all the criteria of being good environmental indicators, as well as having a range of feeding strategies, and being present at multiple trophic levels. The aim of this research was to 1) investigate spatial variation and the effect of urbanisation in trace metal concentration in two native decapod species, Heterozius rotundifrons and Petrolisthes elongatus, which co-occur but feed at different trophic levels; and 2) examine how essential and non-essential trace metals are accumulated into different body tissues of the decapod Jasus edwardsii, a significant cultural and fishery species.  To assess spatial variation and trophic level differences between decapods, baseline data of the concentrations of thirty trace metals was collected and analysed from both species at three sites in the Wellington region. Little variation was found between the sites, despite their differences in proximity to urban development, but significant differences were found between species, with the consumer H. rotundifrons having higher concentrations of most trace metals than the filter feeder P. elongatus.  To assess trace metal accumulation into tissues of J. edwardsii, an experiment was run exposing juveniles to water doped with an elevated copper and neodymium treatment. Copper was preferentially accumulated into the organ tissue, as was expected for an essential element. Neodymium was accumulated differentially into organ and exoskeleton tissue depending on the treatment, with specimens in the elevated treatment taking it up into the shell rather than the organs. A second experiment was also run to investigate whether moulted exoskeletons would passively absorb copper from their environment, which was shown to be the case.  This research aids in understanding the importance of multiple species monitoring, as trace element accumulation was shown to be highly variable depending on species and metals, and contributes valuable geochemical data on native New Zealand species, which have been little studied in this context.</p>

Burlington Bay, Lake Ontario: Its Paleolimnology Based on Fossil Ostracodes

1996 ◽  
Vol 31 (3) ◽  
pp. 643-671 ◽  
Author(s):  
L. Denis Delorme
Keyword(s):  
Bottom Water ◽  
Agricultural Practices ◽  
Lake Ontario ◽  
Mean Annual Temperature ◽  
Water Oxygen ◽  
Oxygen Conditions ◽  
History Of ◽  
The Impact ◽  
Change In Mean

Abstract The history of Burlington Bay for the last 8,400 years has recorded two significant changes in its environment. The first occurred about 2,540 years ago, resulting from a change in mean annual temperature. This, in turn, changed the chemistry of the bay water. The second change occurred about 125 years ago (ca. 1865 A.D.). This time, it was the impact of agricultural practices and industrialization. Agricultural practices caused the lake to become eutrophic. This rapidly (within 40 years) changed the bottom water oxygen conditions to anaerobic. Industrialization had an impact on the fauna and the flora. Some fauna became locally extinct while some phytoplankton became deformed.

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